It is known for many decades to plug wine and spirit bottles by means of a cylindrical cork stopper which is pressed in the neck of the bottle with a certain compression rate. Although this technique has been used exclusively for a very long time, in recent years the cork stopper was called into question again for various reasons linked mainly to the cost and the quality of the stored wine, in particular the development of the so-called “cork” taste.
Compressible stoppers made of synthetic material were developed as replacements for wine bottle cork stoppers and are being used more and more. These compressible synthetic stoppers are considered neutral relative to the bottled wine, and their cost is easier kept under control than that of cork stoppers. However, they have the disadvantage of having low or no recyclability and are not always being easy to extract. These synthetic stoppers also may evoke an image with consumers of industrial production and low quality.
It is also known that wine bottles can be plugged with screw caps. This plugging technique can be well controlled and the preservation performance is considered similar to that of cork or synthetic stoppers. Furthermore, screw caps are recyclable, at least in theory, after separating the internal liner from the cap. However, especially in Europe, this plugging technique may still be considered reserved for low range wines and wines from the so-called New World.
Bottles provided with internal thread have been known for a long time. Such type of bottle is described, for instance in documents U.S. Pat. No. 2,026,304, FR1170472, U.S. Pat. No. 516,726, U.S. Pat. No. 868,914, U.S. Pat. No. 173,089, U.S. Pat. No. 482,682, U.S. Pat. No. 52,269 and EP0027780.
EP1501738 describes a method for making a ceramic bottle provided with an internally threaded neck. The method consists of the following phases: mating a threaded tube with the lower extremity of a funnel shaped body; positioning the threaded tube and the funnel shaped body on the upper extremity of a two part model and injecting the ceramic material through the body in the model; discharging the excess material by turning the model upside down; separating the body from the model leaving the threaded tube in the neck of the bottle; reducing the threaded tube to ash in order to release the thread.
Automated processes are also known today for the production of glass containers. For instance, in the so-called “blow-and-blow” process, gobs of molten glass are fed in chambers of respective blank molds each provided, in a lower part, with a plunger, movable in vertical direction between a lowered and raised position. Just before the gob enters the mold, the plunger is raised and forms an imprint in the glass surrounding the plunger. The plunger is lowered leaving the imprint in the gob and subsequently, air is blown through the imprint to form the gob into a tubular body, closed at the upper extremity and known in the technical field as a “parison”. The parison is then transferred to a final blow mold in which it is suspended by the neck. Air is again blown in the parison, which inflates filling the whole cavity of the final blow mold, assuming the final form of the bottle.
At a first glance, producing a glass container with internal threaded neck may appear to be simple. In practice, this is not the case, in particular when it comes to industrial production at controlled costs. In fact, it is difficult to produce such containers with threaded neck with a controlled, reproducible and robust process, which is easily transferred from one plant to another or from one production line to another. Furthermore, the production speed of existing machines should be maintained, while controlling the quality produced in the production lines to avoid any glass debris.
JP 62-003028 describes an apparatus for producing an inside screw bottle. A screw is formed on the inner surface of the bottom of the gob by the part of the plunger. The plunger is then lowered under rotation and the counter-blow operation is carried out.
U.S. Pat. No. 1,502,560 describes a machine for making bottles, or similar containers, which are provided within the mouth-portion with an internal screw thread. It uses a mandrel or plunger associated with each mold having a tip portion being provided with a thread which serves to form a thread within the mouth of the bottle.
Other manufacturing processes mainly proposed in the first half of the 19th century are described in GB 132,589, U.S. Pat. No. 2,215,984, DE 183525, U.S. Pat. No. 1,406,722, FR 697,986, U.S. Pat. No. 1,560,158, BE 488693.
However the equipment described therein uses complicated mechanisms to generate a rotational movement of a screwed tap which seem to be prone to failure and need a lot of space making it difficult to be used with today's manufacturing equipment. Furthermore, the parison forming operation as shown therein is time-consuming and may slow down the production speed. Moreover, those methods imprint a single thread with small pitch and several turns in the container, making the container unergonomic and cumbersome to open and to close for the user.
Therefore, it is an object of the present invention to provide a fast and efficient process for the fabrication of glass bottles with an internally threaded neck.
Another object of the present invention is to provide a structurally simple and reliable equipment for the fabrication of glass bottles with an internally threaded neck, which can be used within existing glass container manufacturing machines with minimum change of the existing equipment.
A further object of the invention is to provide a glass container which can be produced with the method and/or equipment of the present invention, specifically a bottle for holding wine and/or spirits, with an internally threaded neck which can be opened and closed quickly and ergonomically while still providing good sealing capabilities.
The objects of the invention are achieved by subject matter of the independent claims. Preferred embodiments are defined in the dependent claims.
According to a first aspect, the present invention relates to a process for the fabrication of glass containers, preferably bottles, provided with an internally threaded neck/mouth comprising the steps of: a) feeding a gob of molten glass inside the chamber of a first mold equipped with a tap or plunger having at least one helical rib or groove on its outside surface; b) extracting the plunger from the partially solidified glass by a roto-translational motion, wherein said plunger is rotated around a longitudinal axis coaxial to the outside surface with said at least one helical rib or groove while being longitudinally extracted, in order to unscrew the plunger from the partially solidified glass, leaving a threaded imprint in the glass portion corresponding to the mouth of the container to be produced; c) blowing air into the mouth until the container is formed.
The roto-translational motion for the extraction of the plunger in step b) is generated as follows: A linear actuator acts on the plunger, thereby effecting a linear movement of the plunger along said longitudinal axis and relative to a guide body which is fixed relative to the first mold and surrounding the plunger in said step b). A helical guide being coaxial to the longitudinal axis is provided between said guide body and said plunger and directly transforms said linear movement effected by said linear actuator on said plunger into said roto-translational motion of said plunger. In the production process the gobs are fed in sequence in the chamber of the first mold and the phases a), b) and c) are repeated for every gob.
Advantageously this type of drive mechanism is simple, reliable and well suited to be used with already existing glass production machines, e.g. existing I.S. machines and requires only minimum adaptations of the existing machines. In particular a pneumatic or hydraulic piston drive or a servo-electric drive, being coaxial to the plunger can still be used. Using a helical guide coaxial to the plunger to transform the linear movement effected by the piston or servo-electric drive drive can advantageously be provided within the restricted space of such a machine.
Advantageously, the process is well suited for internal threads in the neck with specifically desired thread geometries. For imprinting such an internal thread in the container neck the at least one helical rib or groove winds around said longitudinal axis over a predefined angle and the plunger is rotated over an angle of rotation equal to or greater than said predefined angle in said roto-translational motion in step b), wherein the angle of plunger rotation is preferably smaller than 360°, more preferably smaller than 200° and according to a preferred embodiment only 90°+/−30°, allowing to maintain a high production speed.
Therewith, a high production speed can be maintained. Furthermore, this allows the production of a neck with an internal thread of coarse pitch and small angular extension around said longitudinal axis (azimuth angle), which can be advantageous for certain applications, e.g. for wine or spirit bottles.
Preferably, said guide body is realized as a thimble which engages the neck ring and longitudinally guides the plunger and the helical guide is provided between the thimble and the plunger. In said steps a) and b) the thimble is fixed relative to the first mold by engaging the neck ring and after extracting the plunger the thimble is moved away down out of engagement with the neck ring.
According to a preferred embodiment of the invention, the fabrication process is a blow-and-blow process, wherein                said first mold is a blank mold and in a step b1) after extracting the plunger the gob is blown to form a parison inside the chamber of said blank mold,        in a step b2) said parison is transferred from the blank mold in a chamber of a blow mold,        in step c) said parison is blown to form the container inside the chamber of the blow mold.        
According to a second aspect, the present invention relates to equipment for the fabrication of glass containers provided with an internally threaded neck, comprising: a first mold delimiting an internal chamber; a plunger movable between a first position, in which it is located inside the chamber delimiting a volume, in negative, corresponding to the mouth of the container, and a second position, in which it is extracted from said chamber; a moving device operatively coupled to the plunger in order to move it from the first position to the second position. The plunger has at least one helical rib or groove on its outside surface and the movement between said first and second position is a roto-translational motion to unscrew the plunger from the glass portion corresponding to the mouth of the container to be produced. The roto-translational motion of the plunger when it is extracted from the imprint which corresponds to the mouth of the container to be produced allows to release the plunger off the mouth without damaging the internal thread formed in it. The roto-translational motion is generated with the following equipment:                a linear actuator which acts on the plunger, thereby effecting a linear movement of the plunger along said longitudinal axis between said first and second position;        a guide body being fixed relative to the first mold and surrounding the plunger, wherein the plunger is movable relative to the guide body along said longitudinal axis; and        a helical guide coaxial to the longitudinal axis and being provided between said guide body and said plunger wherein said helical guide directly transforms said linear movement effected by said linear actuator on said plunger into said roto-translational motion of said plunger between said first and second position. Again, this allows to maintain the production speed and to use the equipment in existing machines with minimum changes.        
According to a preferred embodiment of the invention, the plunger has a work portion in the form of a mandrel extending in the neck ring of the first mold in step a) and a base located below the neck ring. Said at least one helical rib or groove forming said internal thread in the container neck is provided on the circumferential outside surface of the mandrel.
Preferably, the linear actuator comprises a pneumatic or hydraulic piston drive or a servo-electric drive and a driving rod, all being arranged coaxially with the plunger and the first mold. The driving rod is movable coaxially with said longitudinal axis and has a terminating head portion being longitudinally fixedly connected to the base of the plunger.
Preferably, the terminating head portion of the driving rod has an upper flange and the base of the plunger has a lower flange. The flanges of the terminating head portion and the base are engaged by a clamp, e.g. a split ring to connect the terminating head portion of the driving rod and the plunger base.
The flanges of the terminating head portion of the driving rod and the plunger base are slidingly engaged with each other to allow for relative rotation between the driving rod and the plunger base. Thus, the plunger may carry out the roto-translational motion, while the driving rod is purely linearly moving without rotational motion component. Therewith, the equipment can be simply retrofitted in existing machine constructions.
Preferably, said at least one helical rib or groove winds around said longitudinal axis over a predefined angle γ1 (azimuth angle), which is preferably smaller than 360°, more preferably smaller than 200° and according to a preferred embodiment γ1=90°+/−30°. The plunger is rotated over an angle of rotation equal to or greater than the predefined angle γ1, but preferably not more than 360°.
This geometry allows for rapid disengagement of the plunger from the threaded mouth.
Preferably m helical ribs or grooves are provided on the plunger, wherein m is greater than or equal to two, thus forming a multi-turn thread with m independent thread turns. According to a preferred embodiment m is chosen between three and five, preferably is equal to four. The m ribs or grooves are preferably angularly staggered by an angle equal to 360° divided by m.
Furthermore, the helical guide has the same pitch angle as the at least one helical rib or groove on the outside of the plunger which imprints the internal thread in the glass portion corresponding to the mouth of the container to be produced.
Preferably, said at least one helical rib or groove has a pitch angle β1 (angle between the at least one rib or groove and a plane perpendicular to the longitudinal axis) of between 30° and 50°. It has turned out that a particularly preferred pitch angle is β1=37°+/−5°, allowing for a smooth transformation of the linear movement to the roto-translational motion on the one hand side. On the other hand side, these geometric characteristics result in a thread that guarantees secure engagement and tight holding of a cork stopper and, at the same time, easy and fast extraction of the plunger during the mass production phase of the containers.
As already indicated, the plunger has preferably a work portion or mandrel on which the at least one helical rib or groove forming said internal thread in the container neck is provided and a base for connecting with the plunger rod. According to a preferred embodiment of the container to be produced the mandrel has a thread-free ring below the ribs or grooves on its outside surface to form a thread-free portion of the container mouth adjacent to the finish of the container. This can be advantageous in view of the sealing properties of the container when being closed with a cork stopper.
Preferably, the helical guide comprises at least one helical slot made in the outside surface of the base of the plunger or in an internal surface of the guide body and at least one pin solidly connected to the guide body or to the base of the plunger. Said pin is engaged and slides in said helical slot to transform the linear movement effected by the linear actuator into said roto-translational motion of the plunger.
This type of construction is relatively simple and therefore reliable. With this type of construction it is facilitated to apply the invention with already used equipment without necessitating a replacement of the blank mold or the addition of exceedingly other components to the production line.
Preferably, said at least one helical slot winds around said longitudinal axis over an azimuth angle γ2 equal to or greater than said predefined azimuth angle γ1 of the at least one helical rib or groove.
Preferably, said at least one helical slot winds around said longitudinal axis over an azimuth angle γ2 smaller than 360°, more preferably smaller than 200° and according to a preferred embodiment over an azimuth angle of γ2=90°+/−30°.
Further preferably, the helical guide comprises n independently starting helical slots, with n greater than or equal to two, and the n helical slots are staggered angularly by an angle equal to 360° divided by n.
In accordance with the preferred pitch angle β1 of the helical ribs or grooves in the plunger mandrel, the at least one helical slot has a constant pitch angle β2 between 30° and 50°, preferably a constant pitch angle of β2=37°+/−5°.
With the afore-mentioned method and equipment a glass container, specifically a bottle, is producible which is provided with a neck with approximately cylindrical form suitable for plugging the container with a stopper inserted in said neck. Said neck has an internal thread for reversible plugging and unplugging of the container by unscrewing and screwing of said compressible stopper, respectively. With the method and equipment of the present invention in particular a wine or spirit bottle can be produced which has a neck with an internal thread comprising two or more independent thread turns imprinted by the ribs or grooves on the outside surface of the mandrel and having a constant pitch angle β of between 30° and 50°, while the method and fabrication equipment is not necessarily limited hereto.
Preferably, the thread turns in the container neck wind around the longitudinal axis over an angle of rotation (azimuth angle) γ of less than 360°, more preferably between 45° and 200°, and more preferably of γ=90°±30°.
According to a preferred embodiment the ribs or grooves in the plunger mandrel and therewith the thread turns in the container neck extend over a height h3 of between 5 mm and 20 mm along the longitudinal axis.
Preferably the internal thread of the container neck comprises between 3 and 5 independent thread turns.
Further preferably the neck comprises an internal thread-free sealing ring extending from the finish of the container to the beginning of the thread turns made by the thread-free ring below the ribs or grooves on the outside surface of the mandrel. In other words, the thread turns inside the container neck do preferably not extend to the container finish, but have an upper end at a distance of about 2 mm to 5 mm to the container finish.
In accordance with the ribs or grooves on the outside surface of the mandrel, the independent thread turns of the internal thread of the neck are identical and distributed at regular angular intervals over the internal wall of the neck. The independent thread turns of the internal thread have a preferred radial thickness of between 1 and 3 mm.
With such an internal thread, the container has the advantage that it can be plugged and unplugged by simple screwing and unscrewing of a compressible stopper, e.g. a cork stopper, provided with a head suitable to be grabbed by hand and a body suitable for insertion in the threaded neck and conforming during the insertion. This kind of plugging solution seals the container tightly, while providing great ease and practicality of use for the user, who can indefinitely plug and unplug the container by the simple manual operation of screwing and unscrewing the stopper in the neck of the container without to much effort. Furthermore, this kind of plugging solution preserves the high range image of the product held in the container by retaining, for instance, a natural cork stopper with the advantages of a metallic or plastic screw cap.
Other characteristics and advantages of the present invention will become apparent from the exemplary and non-limiting description of a preferred, but not exclusive example of a process and equipment for the fabrication of glass containers provided with internally threaded neck and such glass container, as illustrated in the attached drawings.